Combination swimming pool filter, surface skimmer and water level control device

ABSTRACT

A swimming pool filter unit comprising filter and sand layers, some of the sand cleanable by removing a containing basket, the unit also having automatic pool fill control and overflow drain means.

2l0/ I28, I29. I69, 238, 282, 283. 317

References Clted UNITED STATES PATENTS l0/l957 2l0/l69X 7/l958 Cavehahetal.............. 2l0/l69X A swimming pool filter unit comprisingfilter and sand layers, some of the sand cleanable by removing a theunit also having automatic pool fill control and overflow drain means.

soj rule a Primary Examiner- Frank A. Spear. Jr. Anomey Daniel P.Chemoff ABSTRACT:

containing basket rg,0reg. 97132 210/128, 2l0/l69,2l0/3l7 E04I|3l20 DaleDelphla Route 3, Box 164 A, Newbe [2|] Appl. No. 7,561

Feb. 2, 1970 [45] Patented Nov. 9, 1971 SURFACE SKIMMER AND WATER LEVECONTROL DEVICE 23 Clalnu, 5 Drawing Figs.

United States Patent [72] Inventor [22] Filed [54] COMBINATION SWIMMINGPOOL FIL'IE [51] Int.

I m I I 1 1 I I I I 1 z 1 I 1 I I 1 I u PATENIEDRUV 9 l9?! 3,51 8 774SHEET 1 [IF 2 FIG. 1

FIG. 2

PATENTEmuv 9 19?: 3, 18,774

sum 2 OF 2 (73 mm: sounca GRAVITY OVER" FLOW DISCHARGE FIG. 4

WASTE DRAIN 59J 52) COMBINATION SWIMMING POOL FILTER, SURFACE SKIMMERAND WATER LEVEL CONTROL DEVICE BACKGROUND OF THE INVENTION Thisinvention relates to fluid-filtering devices and more particularly to aswimming pool filter unit utilizing a sandbased filtering medium forcleansing water of impurities, the unit also being provided, as anintegral part thereof, with means for skimming and collecting leaves andother debris, and means for automatically controlling the water level inthe swimming pool tank.

Water-filtering devices especially adapted for use in smallclosed-circulation swimming pools for skimming and collecting leaves,bugs and other debris and thereafter cleansing minute impurities fromthe water prior to its recirculation to the pool tank have long beenknown to the art. It is highly desirable to provide in such poolinstallations a filter unit a type which does not require periodicbackwashing of the filter medium in order to cleanse the unit, as thetens of gallons of waste water produced in the backwashing processrepresents a sizeable cost in water charges to the pool owner,especially in the warmer climates where pools are more prevalent.Further, filters of the backwash type require additional piping andvalve connections as well as fairly complex cycle control means, thusfurther increasing the cost of the filter installatron.

In an effort to reduce the cost and running expense of the filter unit,especially for small residential swimming pool installations, filtershave been developed for use in this specific application employingfiltering elements or mediums which can be readily removed from thefilter unit for periodic cleaning or replacement. Of the more popularfilter units of this type are those described in Pace U.S. Pat. No.2,826,307 and Cavenah et al. U.S. Pat. No. 2,844,255 which utilize afilter element in the form of a tubular core provided with a pluralityof perforated filter plates which is cleaned by removing the elementfrom the filter unit and rinsing it with a garden hose or the like. Uponremoval of the filter element for cleaning, the filter container can, inwhich a dirty slurry remains, must still itself be backwashed by pumpingthis residue to a waste line. To effectuate the filtering action,removable filters of the Pace and Cavenah et al. type employ a filterclay such as diatomaceous earth to trap the minute impurities carried bythe water. The filter clay which collects on the inlet openings of thefilter plates is washed away in the cleaning process and thus must beperiodically replenished in the filter unit. In addition to the messyand distasteful chore, from the pool operators standpoint, of rinsingaway the dirty residue from the filter plates in order to cleanse theelement, the regular replacement of diatomaceous earth or other suitablefilter clay substantially increases the operating costs for the swimmingpool system.

Because of these respective deficiencies of the conventional backwashingand removable types of filter units there has been a longfelt need for aswimming pool filter unit, particularly adapted for the smaller tankinstallation used in private residences, which would be simpler to cleanan more economical to install and operate than those heretofore known tothe art.

In addition to the above-mentioned disadvantages of conventional typesof filtering devices, swimming pool installations typically employ aplurality of discrete individual components, separate from the filterunit and coupled thereto by lengths of piping, to regulate the waterlevel in the swimming pool tank within a prescribed range, i.e., addingwater to the system when the level drops too low and alternativelydraining away excess water when the level reaches a predeterminedmaximum height. The field connection of the filter unit to these waterlevel regulator elements, and the added plumbing costs and materialsnecessitated thereby, materially increase the cost of the watercirculation portion of the swimming pool installation.

SUMMARY OF THE INVENTION The present invention discloses a removable,readily cleaned nonbackwashing type of filter element of novel andinexpensive design for a swimming pool filter unit. The filter iscombined with a surface skimmer and an automatic water level controlmeans to form a compact factory-assembled integral unit which eliminatesa considerable amount of the labor and material cost associated with thecoupling up of these individual components in a conventional poolinstallation. The filtering portion of the unit, in addition to having aremovable wire mesh basket for collecting leaves, bugs and other debriscollected at the inlet of the unit, comprises a cylindrical verticaltank fitted at its top with a removable lid provided with a pair of flowadjustment means therein for regulating the flow of water therethrough.Water entering the filter unit, both from the surface of the pool aswell as at a second entry point coupled to the bottom of the pool, isdrawn by pump action through a sand-filtering medium, the filtered wateris exhausted from the filter unit at the bottom through a suitableunderdrain element whose openings are sufficiently small to prevent sandparticles from draining therethrough. The now-purified water isthereafter drawn through the pump and then returned to the pool forrecirculation.

The top portion of the sand beds contained within a cylindrical meshbasket whose base is formed of a water-permeable grid of mesh sizesufficiently small to prevent passage of sand particles therethrough. Byfar the greater percentage of dirt and other impurities contained in thewater passing through the filter is trapped in this initial portion ofthe sand bed. The remaining portion of the sand bed, constituting thegreater bulk of the total depth of filtering medium contained in theunit, remains substantially uncontaminated in the course of operation ofthe filter since only a small amount of the impurities contained in thewater supply avoids extraction in the initial portion of the sand bed.The mesh basket containing the topmost portion of the filtering mediumis readily removable from the unit so that the sand contained thereincan be dumped out together with its entrapped residue and the basketrefilled with a fresh supply of sand at sufficiently regular intervalsto prevent its becoming saturated with residue material from the watersupply. Since sand is quite inexpensive and only a small portion of thetotal sand bed need be replaced in order to empty out the dirt particlesentrapped in the filtering medium, the material costs for runningoperation of the filter unit are minimal. The lower portion of the sandbed, that is, the sand depth below the bottom of the mesh basket,remains relatively clean during the course of operation of the unitfunctioning essentially as a polishing agent on the water, and need notbe replaced except at relatively long intervals. Preferably, the lowerportion of the sand filter bed is comprised of a layer of somewhatcoarser particles than that in the upper portion so as to permit use ofa water underdrain element in the filter unit having larger water inletopenings than would be feasible if fine sand were used throughout.

Immediately preceding the filter portion of the unit there is provided afloatation-type weir in the water inlet to the unit positioned so as toskim the surface of the pool water as it spills over into the filter. Inaddition there is integrally formed on the filter unit near its inletand at the waterline of the pool a compartment housing a water levelcontrol means in the form of an automatic fill device acting inconjunction with an overflow drain to maintain the water level of thepool within predetermined limits. The filter unit is further providedwith water flow control means and a shutoff valve on its water inlets toconvert the unit for vacuum-cleaning operation.

It is therefore a principal objective of the present invention toprovide a new and improved nonbackwashing-type swimming pool filterwhich is easier to maintain and less costly to manufacture and operatethan filter units heretofore known to the an.

It is a further objective of the present invention to provide a swimmingpool filter unit of the type described containing as an integral partthereof means for skimming the surface of the pool waterline andautomatic means for maintaining the water level of the pool withinpredetermined limits.

It is a principal advantage of the filter unit of the present inventionthat the filter medium employed is comprised of inexpensive and widelyavailable sand material in contrast to more costly special filteringclays, and that only a portion of the filtering medium need bereplenished in the regular maintenance of the filter unit during thecourse of a season.

It is a further advantage of the filter unit of the present inventionthat the filtering element can be readily and neatly removed from theunit, cleaned, refilled and replaced in a minimum of time and withoutnecessitating any draining of the swimming pool or disabling of anycontrols to the swimming pool installation.

It is a principal feature of the present invention that a singlefactory-built compact unit combines the functions of filtering, surfaceskimming and automatic water level control so that it can be quickly andinexpensively installed at the job site with a minimum of labor andmaterials for connection.

The foregoing and other objectives feature and advantages of the presentinvention will be more readily understood upon consideration of thefollowing description of the invention, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view,partially broken away, showing an illustrative embodiment of a swimmingpool filter unit in accordance with the present invention.

FIG. 2 is a front sectional view of the filter unit of FIG. 1 installedin the wall of a swimming pool.

FIG. 3 is an exploded, perspective view of a detail of the filter unitshown in FIG. 1 illustrating the components of the filter which areremoved for cleaning of the filter.

FIG. 3A is an enlarged front sectional view, taken along the line 3A-3Aof FIG. 3, showing the wire mesh basket which contains the upper portionof the sand bed.

FIG. 4 is a schematic diagram showing a typical hookup connection of thefilter unit to a swimming pool installation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the FIGS., thefilter unit of the present invention, designated generally as 10, isinstalled in the wall 12 of a pool tank 15 having a usual surface waterlevel 17. The filter unit is in the form generally of a verticalcylindrical tank comprised of three major portions: (a) a surfaceskimmer provided by weir 20, (b) a debris trap and rapid sand filtrationelement 30, and (c) an automatic water level control means consisting ofa water intake valve 70 and an overflow drain 80.

An inlet passage 19 formed in the upper sidewall of the filter unitcommunicates through the pool wall 12 to the pool tank 15. Water fromthe pool is drawn into and through the rapid sand filter unit 10 by thesuction or negative pressure produced by a pump 50 (FIG. 4) which may beof any suitable design capable of handling swimming pool circulatoryflow requirements of the order of 20 gallons per square foot per minute.After passage through the pump the water is recirculated to the tank viaa wall outlet 54 coupled to the pump discharge by line 52.

A fiat disc-shaped lid 32, provided with finger-grasping holes 33 topermit ready removal, sits on the interior shoulder of a circular endflange 34 provided on the top edge of the cylindrical wall 31 of thefilter unit so as to provide a protective close over the top of theunit. The lid 32 and the support ing end flange 34 are preferablyconfigured so that the lid lies flush with the level of the tile wall 12and deck surface 14 surrounding the pool.

After being skimmed by passage over the weir 20 the surface water 17,drawn in by the pump 50, passes downward into the filter unit throughinitially a debris basket 36 formed of screen wire mesh whosecylindrical sidewall nests snugly with a minimum clearance against themating interior wall surface 31 of the unit and is supported by legs 37bwhich rest on top of a cover plate member 38. To permit removal, andalso to reinforce and strengthen the screen structure of the basket 36,a welded-wire handgrip 37a is secured at spaced points around the upperperiphery of the debris basket. This debris basket 36 acts as a grossfilter to trap leaves, bugs and other relatively large-scale debrisfloating on the top of the pool.

Next in sequence from the debris basket is a circular cover plate member38 which contacts the cylindrical sidewall 31 of the unit and rests onan inwardly projecting shoulder 39 formed thereon. The cover plate 38 isbowed slightly upwardly into a convex shape and is provided with arecessed handhold 40 to facilitate its removal from the filter unitduring the cleaning operation. The cover plate nests snugly against theshoulder 39 and adjacent sidewall 31 to provide substantially awatertight seal so that water passage through the member is providedexclusively by openings 41 therein which are fitted with adjustable flowcontrol devices 42. The flow control devices may comprise, for example,a pair of coaxially mounted perforated discs which may be rotated inrelation to each other so as to vary the size of the aperturespermitting water to pass therethrough.

Immediately beneath the cover plate member 38 is a second inlet passage43 which is coupled to a conduit line 44 drawing water from the bottomof the pool tank 15 (FIG. 4). The passage 43 is preferably in the formof a threaded pipe stub so as to readily connect with a conventionaltubular pipe line. As a convenience in installation, an alternate inletpassage 43a is provided in the filter unit sidewall at a diametricallyopposed location, and when not in use the alternate pipe stub may besealed off with plug 46. Thus in the region of the filter unit justbeneath the cover plate 38 the water from the surface of the pool, nowskimmed and cleansed of debris, is mixed with water drawn from the poolbottom, and the resultant mixture is drawn through the filter bed of theunit under the action of the pump 50.

The sand bed is situated in the lower and bottom portion of the filter30 and acts as a filtering agent on the water drawn from the poolsurface and bottom before it is exhausted from the unit throughunderdrain element 45. The sand bed preferably consists of two layers, afirst layer 51 being constituted by sand of relatively fine size, on theorder for example of No. 16 mesh; and a second lower 52 of somewhatcoarser size, on the order for example of No. 8 mesh. By the term sandis meant conventional silica sand material, pulverized volcanic rockmaterial or other particulate material providing comparable filteringaction.

The top stratum 51a of the first layer of fine sand 51 is containedwithin a cylindrical basket member 60, constructional details of whichare best shown in FIG. 3A. If desired, filter paper or other disposableforaminous sheet material (not shown) may be provided overlying theupper surface of the top stratum 51a so as to assist in the filteringaction and thereby reduce the thickness of the sand layer required inthis stratum. The basket is provided with a wire screen bottom 61supported on a wire grid frame 62 and having a mesh size slightlysmaller than the particulate size of the sand 51 contained therein. Inthis matter the upper stratum portion of the sand layer 51 will remainin the bottom of the basket 60 when the latter is removed from thefilter unit, although water at all times is free to pass substantiallyunimpeded therethrough. A wire handhold 63 is provided and secured atspaced points around the upper periphery of the basket 60 to assist inthe removal of the member from the unit during the cleaning operation.The upper portion of the cylindrical sidewall 69 of the basket member isperforated by a plurality of spaced apertures 65 which permit the watercontained on the top of the sand layer 51 to drain out radially from thesidewall as the basket member is removed upwardly from the filter unitin the course of the cleaning operation.

As best shown in FIG. 2, in the normal running mode of the filter unitthe basket 60 is supported on an interior shoulder 67 formed in thecylindrical sidewall 31 of the filter unit and in watertight sealingengagement therewith by means of a compressible O-ring gasket 68. Thebasket is filled with a stratum of sand 51:: to about half its height,so that the sand level is just beneath the lower ring of apertures 65provided in the upper reach of the baskets sidewall 69. The sand stratumcontained in the basket 60 is preferably of the same grade, quality andsize as that contained in the lower stratum portion 51b of the firstsand layer, although this is not necessarily so since the filter unitmay be feasibly used with sand of differing quality and size inrespective strata 51a and 51b. However, it is apparent that the filterunit is easier and more economical to operate and maintain if the sandbed is fonned of, at most, two different sand materials, and theutilization of a third sand differing in size, grade or quality from anyof the other two would introduce needless complications and expense;although it is to be understood that there is no substantial functionimpediment to utilizing differing sand materials to form the respectivestrata 51a and 51b. The depth of the sand strata 51a contained withinthe bottom of the basket 60 would be on the order of l I, to 2 inches ina typical embodiment of the filter unit of the present invention inwhich the entire sand bed comprised of layers 51 and 52 would be of atotal depth of 12 to 14 inches.

In the illustrative embodiment shown the filter bed strata 51a and 51bare formed of the same sand material. In operation the upper strata 51atraps virtually all of the dirt and other minute impurities contained inthe pool water, and only a minimal portion of this foreign matterpenetrates into the lower stratum 51b so long as the upper stratum 51ais regularly removed and replenished with fresh filter material. Thus,in effect, the lower stratum 51b forming the first layer of the sand bedacts essentially as a polishing agent and accordingly need only bereplaced on an infrequent basis, perhaps once every several years. Thelower layer 52 of somewhat coarser sand in the upper layer 51 and theunderdrain element 45 so as to permit the apertures in the latter,through which the filtered water is exhausted from the unit, to be ofnominal size rather than subminiature as would be the case if theunderdrain element were in direct contact with the fine-sized sandparticles constituting the first layer 51. The underdrain element 45 maybe of any suitable type known to the art for exhausting water from thebottom of the filter unit while preventing the draining of sand or otherfilter material therethrough.

As depicted in the exploded view of FIG. 3, the filter elements may bereadily removed from the unit for cleaning by merely lifting themvertically upward through the top opening which is normally covered inuse by the lid 32. After removal of the lid the debris basket 36 isaccessible and can be lifted out for dumping and then replacement. Thiscan be done as fzequently as necessary without inhibiting thecirculation of pool water through the filter unit or otherwisedisturbing the other elements of the device. On a regular, but far lessfrequent basis, when the debris basket 36 is removed for emptying, thecover plate member 38 is also removed exposing the underlying basket 60containing the upper stratum 51a of filter sand. This latter basket islifted upward and, as it is removed, the water carried in the containerand resting on the top of the sand strata quickly drains off through theradial openings 62 provided in the basket sidewall 69. in this manner,by the time the basket 60 is withdrawn through the top collar 34 of thefilter unit, most of the water has drained back in the unit and only asmall amount of water remains as the residue in the basket to drip outas the element is carried off for dumping of the waste material. Afterdumping of the sand strata 51a containing the trapped dirt impuritieswhich have been extracted from the pool water, the strata isreconstituted with new sand and the basket 60 thereafter replaced intothe filter unit with the remaining elements following in reverse orderfrom the sequence of their removal from the unit.

it is to be especially noted that the aforementioned filtercleaningoperation does not necessitate the shutdown of the pool circulation, nordoes it permit dirty water to be circulated through the filter lines andfilter pump for reintroduction into the pool, as even with the baskettemporarily removed the lower strata of fine sand 5 lb remains in theunit to cleanse the water in that short period of time during which thesand basket is being cleaned. With periodic servicing of the sand basket60 and the replacement of the upper stratum 51a as it becomes saturated,the lower stratum 51b as well as the underlying second layer 52 willstand up for a long period of time, typically an entire season, withoutneed for replacement.

Turning away now from the filter element 30, the unit is additionallyprovided with means for maintaining automatic water level control in theswimming pool tank. A compartment is formed out of the upper sidewall 31of the unit, preferably at a position diametrically opposed from that ofthe inlet passage 19, which communicates with the water level in thepool 15. Across the face of the opening connecting the compartment 75 tothe interior of the cylindrical filter unit an apertured baffle 72 ispositioned so as to prevent the entry of debris into the compartment andalso to dampen wave oscillations in the water level 17 as it enters fromthe tank into the compartment.

Positioned in a wall of the compartment is an automatic fill devicewhich may exemplarily be in the form of a spring-actuated float valve 70which automatically opens to permit water to enter when the pool level17 drops below a predetermined minimum threshold. Fresh water isdelivered to the valve opening 70 via a conduit line 72 connected to awater source 73. Thus, if the water level should drop below apredetermined minimum level, the float 70a connected to the top of aspring-biased lever arm 70b drops downward in a vertical arc, therebyopening the valve and permitting water to enter from the supply line 72into the compartment to restore the level of water in the pool tank.

in the same compartment 75, and also positioned on a wall thereof, is agravity-fed overflow device in the form of a tubular aperture whichcouples to a discharge line 82 for draining away water from the poolwhen the pool level 17 reaches or exceeds a predetermined maximumthreshold. Adjustment of the spring bias on the lever arm 70b of theautomatic fill device 70 permits adjustment of the range separating theminimum threshold level at which water is automatically introduced intothe pool from the maximum threshold level at which water commences todrain out through the gravity discharge device 80.

To convert the filter unit for vacuum-cleaning operation a suitablevacuum attachment device (not shown) is coupled to one or the other ofthe two openings 41 formed in the cover plate member 38 (the lid 32 anddebris basket 36 having previously been removed to permit access to thecoupling juncture), and the flow passage in the other of the twoadjustment means 42 concomitantly closed down to shut off or minimizethe flow of water therethrough. The pump 50 will in this mode ofoperation then draw water through the filter device and the vacuumattachment under high suction, permitting rapid vacuum cleaning of thetank walls of the pool in the conventional manner.

The filtration system is also designed so that all of the water may beconveniently and expeditiously drained from the pool, when desired, byshutting off the two flow apertures 42 passing water from the surface ofthe pool, closing down valve 57 in the recirculating line 52, andconcurrently opening valve 58 in waste line 59 connecting to a drain.

The terms and expressions which have been employed in the foregoingabstract and specification are used therein as terms of description andnot of limitation, and there is no intention, in the use of such termsand expressions, of excluding equivalents of the features shown anddescribed or portions thereof, it being recognized that the scope of theinvention is defined and limited only by the claims which follow.

What is claimed is:

l. A filter unit for a swimming pool comprising:

a. a vertically positioned container of generally tubular form havingwater ingress means at one end communicating with the surface waterlevel of said pool and water egress means at the other end coupled to apump for drawing water from said pool through said container,

b. a debris basket in said container following said water ingress meansfor collecting leaves, twigs, bugs and other large scale debris,

c. a layer of fine sand material in said container following said debrisbasket, said layer being of sufficient thickness to trap minuteimpurities carried in the water passing through said unit, and

d. a removable basket having a foraminous bottom of mesh size finer thanthat of said sand material, said basket being positioned in said sandlayer and containing therein the upper portion of said sand layer.

2. The filter unit of claim 1 further provided with an additional wateringress means in said container positioned between said debris basketand said sand layer and coupled to a water drain in the bottom of saidpool so that water from said pool bottom is also drawn through saidfilter unit.

3. The filter unit of claim 2 further characterized in that a coverplate member is positioned in said container between said debris basketand said additional water ingress means and is provided with flowcontrol means for adjusting the amount of water drawn from said poolsurface through said filter unit by said pump.

4. The filter unit of claim 3 wherein said cover plate member is in theform of a circular disk of solid material in watertight sealingengagement with the interior wall surface of said filter container andsaid flow control means is in the form of a plurality ofvariable-diameter apertures in said cover plate member.

5. The filter unit of claim 4 wherein said filter unit is adapted forvacuum-cleaning operation by closing off all but one of said aperturesin said cover plate member and connecting a vacuum-cleaning hoseaccessory to the other of said apertures.

6. The filter unit of claim 1 further provided with a weir of buoyantmaterial pivotably mounted in said water ingress means for skimming thesurface of said pool water drawn into said unit.

7. The filter unit of claim 1 further characterized in that acompartment is formed on the vertical wall surface of said containerhaving a passageway communicating with the surface water level of saidpool, said compartment containing (a) a float valve means controllingthe addition of water to the pool from a water supply source, said floatvalve automatically opening to permit the flow of water therethroughwhen the pool level drops below a predetermined minimum threshold, and(b) an overflow device coupled to a discharge line for draining awaywater from the pool when the pool level reaches a predetermined maximumthreshold.

8. The filter unit of claim 7 wherein an apertured plate is interposedin said passageway connecting said compartment to said filter containerfor the purposes of both preventing the entry of debris into saidcompartment and dampening wave oscillations in water entering saidcompartment.

9. The filter unit of claim 1 further characterized in that said sandlayer is comprised of two strata of differing mesh size, the firststratum, a portion of which is contained inside said basket, having aparticle size substantially smaller than the second stratum of sandmaterial which is located beneath said basket.

10. The filter unit of claim 9 further characterized in that said wateregress means is in the form an underdrain element embedded in saidsecond sand stratum and having apertures therein for extracting waterfrom said filter container which are of smaller size than the particlescomprising said second sand stratum, but of greater size than theparticles comprising said first sand stratum.

H. The filter unit of claim I wherein the foraminous bottom of saidbasket is comprised of a sheet of wire screening of the prescribed meshsize.

12. The filter unit of claim 11 wherein said basket containing the upperportion of said sand layer is further characterized in that it is ofgenerally squat cylindrical form and the sidewall which rises above saidforaminous bottom is nonpervious from said bottom to the normal level ofsaid sand material therein and above said normal sand level saidsidewall is perforated with a plurality of apertures so as to permit thedraining of water radially from said basket when it is withdrawn fromsaid filter unit.

13. The filter unit of claim 1 further characterized in that a coverplate member is positioned in said container between said debris basketand said sand layer and is provided with flow control means therein foradjusting the amount of water drawn from said pool through the filterunit by said pump.

14. A filter unit for a swimming pool comprising:

a. a container of generally cylindrical fonn adapted for verticalmounting on the side of a swimming pool tank and covered by a removablelid member,

b. a first water ingress means in the form of a passageway provided inthe sidewall of said container near the upper end thereof communicatingwith the surface water level of said pool,

c. a removable debris basket of cylindrical form fitting inside saidfilter container and positioned beneath said first water ingress means,

d. a removable cover plate member of circular disc form positionedbeneath said debris basket and in watertight sealing engagement with theinterior wall of said filter container, said cover plate member beingprovided with variable flow control means permitting the passage ofwater therethrough,

e. a second water ingress means mounted in the sidewall of said filtercontainer beneath said cover plate member and coupled to a water drainin the bottom of said pool,

f. a removable basket member nesting inside said container andpositioned beneath said second water ingress means, said basket memberhaving a foraminous bottom,

g. a layer of fine sand material contained within said basket member andhaving a mesh size slightly larger than the openings in said basketbottom, and

h. a water egress means situated in the lower end of said containerbeneath said basket member and coupled to a pump for drawing water fromsaid pool through said container.

15. The filter unit of claim 14 further characterized in that the spaceinside said container beneath said basket member is substantially filledwith sand material.

16. The filter unit of claim 15 wherein said sand filling is comprisedof two strata of differing mesh size, the first stratum locatedimmediately beneath said basket member being of substantially the samemesh size as the sand layer contained in said basket member, and thesecond stratum having a mesh size substantially greater than said firstsand stratum.

17. The filter unit of claim 16 wherein said water egress means is inthe form of an underdrain element embedded in said second sand stratumand having apertures therein for extracting water from said filtercontainer which are of smaller size than the particles comprising saidsecond sand stratum, but of greater size than the particles comprisingsaid first sand stratum.

18. The filter unit of claim 14 further characterized in that saidbasket member is of a generally squat cylindrical configuration, with abottom formed of a sheet of wire screening of the prescribed mesh sizeand a sidewall which is nonpervious from said bottom to the normal levelof said sand layer contained therein and above said normal sand levelsaid sidewall is perforated with a plurality of apertures so as topermit the draining of water radially from said basket when it iswithdrawn from said filter unit.

19. The filter unit of claim 14 further characterized in that acompartment is formed on the vertical wall surface of said containernear the upper end thereof having a passageway communicating with thesurface water level of said pool, said compartment containing (a) afloat valve means controlling the addition of water to the pool from awater supply source, and (b) an overflow device coupled to a dischargeline for draining away excess water from said pool.

20. The filter unit of claim 19 further provided with a weir of buoyantmaterial pivotably mounted in the passageway of said first water ingressmeans for skimming the surface of said pool water drawn into said unit.

21. A compact, integrated filter unit for a swimming pool comprising ahousing containing therein:

a. water ingress means for communicating with the surface water level ofsaid pool,

b. a weir element for surface skimming the pool water entering saidunit,

c. a removable debris basket for collecting large scale debris,

d. a filtration element for extracting minute impurities from the waterflowing through said unit,

e. water egress means for coupling to a pump drawing water from saidpool through said unit,

f. a fill device responsive to the surface water level of said pool forcausing water to be added when the pool level drops below apredetermined minimum threshold, and

g. an overflow device adapted to couple to a discharge line for drainingaway water from the pool when the pool level reaches a predeterminedmaximum threshold.

22. The filter unit of claim 21 wherein said housing further contains anadditional water ingress means adapted to couple to a water drain in thebottom of said pool.

23. The filter unit of claim 22 further characterized in that flowcontrol means are provided in said housing for adjusting the relativeflows of water permitted to be drawn into said unit through therespective water ingress means.

t t i ii i Patent No.

Inventor(s) (SEAL) Antes t 1, Line Line Line Line Line

4, Line 5, Line 6, Line UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Signed and EDWARD II.FLETCHER,JR. Attesbing Officer January17,

Dale Delphia It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

After "unit" insert --of-;

Change "an" to -and-.

Change "beds" to bed-.

Change "feature" to --features--;

Change "close" to -closure--.

After "lower" insert -1ayer.

After "sand" insert -serves primarily as a buffer medium between thefinesized sand-.

Change 70" to 60.

smiled this 16th day of May 1972.

ROBERT GOTTSCHALK Commissionerof Patents ORM PO-IOSO (10-69) USCOMM-DC50375-3 69 U GOVERNMENT PRINTING OFFICE I989 O-365-33l

1. A filter unit for a swimming pool comprising: a. a verticallypositioned container of generally tubular form having water ingressmeans at one end communicating with the surface water level of said pooland water egress means at the other end coupled to a pump for drawingwater from said pool through said container, b. a debris basket in saidcontainer following said water ingress means for collecting leaves,twigs, bugs and other large scale debris, c. a layer of fine sandmaterial in said container following said debris basket, said layerbeing of sufficient thickness to trap minute impurities carried in thewater passing through said unit, and d. a removable basket having aforaminous bottom of mesh size finer than that of said sand material,said basket being positioned in said sand layer and containing thereinthe upper portion of said sand layer.
 2. The filter unit of claim 1further provided with an additional water ingress means in saidcontainer positioned between said debris basket and said sand layer andcoupled to a water drain in the bottom of said pool so that water fromsaid pool bottom is also drawn through said filter unit.
 3. The filterunit of claim 2 further characterized in that a cover plate member ispositioned in said container between said debris basket and saidadditional water ingress means and is provided with flow control meansfor adjusting the amount of water drawn from said pool surface throughsaid filter unit by said pump.
 4. The filter unit of claim 3 whereinsaid cover plate member is in the form of a circular disk of solidmaterial in watertight sealing engagement with the interior wall surfaceof said filter container and said flow control means is in the form of aplurality of variable-diameter apertures in said cover plate member. 5.The filter unit of claim 4 wherein said filter unit is adapted forvacuum-cleaning operation by closing off all but one of said aperturesin said cover plate member and connecting a Vacuum-cleaning hoseaccessory to the other of said apertures.
 6. The filter unit of claim 1further provided with a weir of buoyant material pivotably mounted insaid water ingress means for skimming the surface of said pool waterdrawn into said unit.
 7. The filter unit of claim 1 furthercharacterized in that a compartment is formed on the vertical wallsurface of said container having a passageway communicating with thesurface water level of said pool, said compartment containing (a) afloat valve means controlling the addition of water to the pool from awater supply source, said float valve automatically opening to permitthe flow of water therethrough when the pool level drops below apredetermined minimum threshold, and (b) an overflow device coupled to adischarge line for draining away water from the pool when the pool levelreaches a predetermined maximum threshold.
 8. The filter unit of claim 7wherein an apertured plate is interposed in said passageway connectingsaid compartment to said filter container for the purposes of bothpreventing the entry of debris into said compartment and dampening waveoscillations in water entering said compartment.
 9. The filter unit ofclaim 1 further characterized in that said sand layer is comprised oftwo strata of differing mesh size, the first stratum, a portion of whichis contained inside said basket, having a particle size substantiallysmaller than the second stratum of sand material which is locatedbeneath said basket.
 10. The filter unit of claim 9 furthercharacterized in that said water egress means is in the form anunderdrain element embedded in said second sand stratum and havingapertures therein for extracting water from said filter container whichare of smaller size than the particles comprising said second sandstratum, but of greater size than the particles comprising said firstsand stratum.
 11. The filter unit of claim 1 wherein the foraminousbottom of said basket is comprised of a sheet of wire screening of theprescribed mesh size.
 12. The filter unit of claim 11 wherein saidbasket containing the upper portion of said sand layer is furthercharacterized in that it is of generally squat cylindrical form and thesidewall which rises above said foraminous bottom is nonpervious fromsaid bottom to the normal level of said sand material therein and abovesaid normal sand level said sidewall is perforated with a plurality ofapertures so as to permit the draining of water radially from saidbasket when it is withdrawn from said filter unit.
 13. The filter unitof claim 1 further characterized in that a cover plate member ispositioned in said container between said debris basket and said sandlayer and is provided with flow control means therein for adjusting theamount of water drawn from said pool through the filter unit by saidpump.
 14. A filter unit for a swimming pool comprising: a. a containerof generally cylindrical form adapted for vertical mounting on the sideof a swimming pool tank and covered by a removable lid member, b. afirst water ingress means in the form of a passageway provided in thesidewall of said container near the upper end thereof communicating withthe surface water level of said pool, c. a removable debris basket ofcylindrical form fitting inside said filter container and positionedbeneath said first water ingress means, d. a removable cover platemember of circular disc form positioned beneath said debris basket andin watertight sealing engagement with the interior wall of said filtercontainer, said cover plate member being provided with variable flowcontrol means permitting the passage of water therethrough, e. a secondwater ingress means mounted in the sidewall of said filter containerbeneath said cover plate member and coupled to a water drain in thebottom of said pool, f. a removable basket member nesting inside saidcontainer and positioned beneath said second water ingress means, saidbasket member having a forAminous bottom, g. a layer of fine sandmaterial contained within said basket member and having a mesh sizeslightly larger than the openings in said basket bottom, and h. a wateregress means situated in the lower end of said container beneath saidbasket member and coupled to a pump for drawing water from said poolthrough said container.
 15. The filter unit of claim 14 furthercharacterized in that the space inside said container beneath saidbasket member is substantially filled with sand material.
 16. The filterunit of claim 15 wherein said sand filling is comprised of two strata ofdiffering mesh size, the first stratum located immediately beneath saidbasket member being of substantially the same mesh size as the sandlayer contained in said basket member, and the second stratum having amesh size substantially greater than said first sand stratum.
 17. Thefilter unit of claim 16 wherein said water egress means is in the formof an underdrain element embedded in said second sand stratum and havingapertures therein for extracting water from said filter container whichare of smaller size than the particles comprising said second sandstratum, but of greater size than the particles comprising said firstsand stratum.
 18. The filter unit of claim 14 further characterized inthat said basket member is of a generally squat cylindricalconfiguration, with a bottom formed of a sheet of wire screening of theprescribed mesh size and a sidewall which is nonpervious from saidbottom to the normal level of said sand layer contained therein andabove said normal sand level said sidewall is perforated with aplurality of apertures so as to permit the draining of water radiallyfrom said basket when it is withdrawn from said filter unit.
 19. Thefilter unit of claim 14 further characterized in that a compartment isformed on the vertical wall surface of said container near the upper endthereof having a passageway communicating with the surface water levelof said pool, said compartment containing (a) a float valve meanscontrolling the addition of water to the pool from a water supplysource, and (b) an overflow device coupled to a discharge line fordraining away excess water from said pool.
 20. The filter unit of claim19 further provided with a weir of buoyant material pivotably mounted inthe passageway of said first water ingress means for skimming thesurface of said pool water drawn into said unit.
 21. A compact,integrated filter unit for a swimming pool comprising a housingcontaining therein: a. water ingress means for communicating with thesurface water level of said pool, b. a weir element for surface skimmingthe pool water entering said unit, c. a removable debris basket forcollecting large scale debris, d. a filtration element for extractingminute impurities from the water flowing through said unit, e. wateregress means for coupling to a pump drawing water from said pool throughsaid unit, f. a fill device responsive to the surface water level ofsaid pool for causing water to be added when the pool level drops belowa predetermined minimum threshold, and g. an overflow device adapted tocouple to a discharge line for draining away water from the pool whenthe pool level reaches a predetermined maximum threshold.
 22. The filterunit of claim 21 wherein said housing further contains an additionalwater ingress means adapted to couple to a water drain in the bottom ofsaid pool.
 23. The filter unit of claim 22 further characterized in thatflow control means are provided in said housing for adjusting therelative flows of water permitted to be drawn into said unit through therespective water ingress means.